Furnace



July 8, 1930. F. A FAHRENWALD 1,770,103

FURNACE Original Filed Jan. 18, 1927 rnwnn Illlll a m u N 15 1 .6 PrankAImhrenWdId L 0 Inventor Attornegs Patented 8, 1930 PATENT OFFICE FRANKA. ILHRENWALD, OF CHICAGO, ILLINOIS FURNACE Application filed January18, 1927, Serial No. 161,855. Renewed January 23, 1929.

This invention relates to furnaces-and especially to those of the typehaving internal mechanical conveyors for passing metallic articlesthrough a heated chamber for heat treating purposes, as for example inannealing sheet steel. The objects of the invention are the provision ofnew, improved, and simplified means for conserving heat and maintainingwithin the furnace chamber an atmosphere of the desired chemicalcomposition.

In the drawings I have shown a specimen furnace embodying myimprovements. 'Fig. 1 is a longitudinal section, Fig. 2 an endelevation, Fig. 3 a transverse section, Fig. 4 a detail view of apreferred form of roll; and Figs. 5 and 6 illustrate difierent curvesdefined by the rolls.

The furnace comprises a floor 1, end walls 2, side walls 3, andan'imperforate roof 4, all made of thick, refractory heat insulatingmaterial. I have not illustrated the metallic frame work usuallyemployed for strengthening purposes. This is presupposed. Formed g5 inthe side walls are openings 5, 5, receiving the ends of horizontal rolls6. I have illustrated the hot-type of roll constructed as set forth inmy application filed October 12, 1925, Serial No. 61,989, namely: rollsmade of high temperature alloy and so-designed as to run, without localc oling, at any temperature up to about 2000. F. However the pres- .entfurnace is not restricted to this type of roll.

These rolls are not located in a single plane, but higher inside thebody of the furnace than they are adjacent the two ends thereof. The endwalls are provided with slots 7 for defined by'the rolls may either be acontinuous curve .as shown in Fig. 5 or a flat topped curve the ingressand egress of the sheets or other as shown in Fig. 6. The roof of thefurnace side walls are kept tight. This is not difiicult to accomplishsince the only necessary apertures therein are the apertures 5 for therolls and these can be packed by the use of cover plates 10 having somekind of soft packin 11 therein like asbestos or magnesia. It wilberemembered that the speed of the rolls isveryslow and the gas ressurevery low.

I do not limit mysel f to roll type conveyors nor when rolls are used doI limit myself to any one type or shape of roll. I prefer the roll typefurnace using non-cooled rolls be- *,cause of its simplicity and economybut my invention does not depend thereon. I have shown disk-type rollsin Figs. 3 and 4 because of the fact that many prefer them for sheetfurnaces, but plain cylindrical rolls in Fig. 1 which can also be usedfor sheets and are preferable for bars, pallets, and odd shapes.

do not limit myself to any one kind of heating although I preferelectrical heating for ments 12, 12 in Fig. 4 located above and belowthe rolls. As this type of heatingrequires no gas-flow it is easier tomaintain a uniform chemical condition inside the furnace than with afull fired furnace, and the economy of hot gas produced by the shape ofthe furnace enables electricity to be used economically. Indeed with aproper insulation of the furnace walls and t e use of noncooled rollsthe heat consum tion becomes very nearly proportional to t e tonnage ofmaterial operated on, with only a small heat loss. No doors or otherclosures are required for the slots 7 although their unnecessary orobstructive use does not serve to distinguish from my invention.

Having thus described my invention what I claim is -which purpose I haveshown resistance elev 1. A furnace of the character describedcomprising, in combination, a chambered structure of refractory materialhavin ingress and egress openings, conveyor rol s in said furnace, saidrolls having axial. extensions which traverse apertures formed thereforin the side Wall of said chamber structure, said rolls constituting amechanical conveyor, portions of said conveyor inside the furnacechamber being elevated above the level of said openings and the roof andvvalls of said furnace being substantially gas-tight, and meanspreventing escape of hot gases through the apertures around said rolls.

2. A furnace of the character described comprising, in combination, anelongated chambered structure of refractory material having ingress andegress openings at opposite ends, a mechanical conveyor extendingthrough said furnace from a point outside of said ingress openingto apoint outside of said egress opening, said conveyor comprising a seriesof parallelhorizontal rolls, certain offthe rolls inside the furnacechamber being'elevated above the level of said openings, said rollshaving axial extensions which traverse apertures with which the sidewalls FRANK A.

whereof I hereunto am; my

